Hybrid vehicles that run with power of at least one of an engine and a motor have been known. In a hybrid vehicle, the storage quantity or the state of charge (SC) of a battery provided for supplying power to the motor is controlled to be within a predetermined range. When the SOC of the battery is equal to a lower limit value of the predetermined range or is lower, the engine is forcedly driven to charge the battery with power which is generated by using a driving force of the engine, to thereby restore the SOC of the battery.
On the other hand, while the distance a hybrid vehicle can travel using a motor only must be maximized in order to enhance fuel efficiency, there has simultaneously been known technology for controlling to limit the load on the motor when the temperature of the motor exceeds a predetermined allowable temperature, in order to prevent performance deterioration of the motor.
Patent Document 1 indicated below discloses a hybrid driving apparatus which performs load limitation control for limiting a load applied to a motor when the temperature of the motor exceeds a predetermined temperature. Patent Document 1 discloses that a unit which detects a load mounted state or a traction state of a vehicle is provided and a load limitation start temperature is determined based on the load mounted state or the traction state which is detected. More specifically, when the vehicle is in a traction state and the travel resistance is greater than that in a non-traction state, the load limitation start temperature is set to be lower than the temperature in the non-traction state. Further, when the quantity of traction is great, the load limitation start temperature is set to be further lower than the temperature when the quantity of traction is small. With the above setting, in a state in which a heating limit temperature which is a limit temperature that the motor can resist is determined, the temperature of the motor can be maintained within the range of the heating limit temperature even when the travel resistance is increased due to the large quantity of mounted load or the traction state to thereby increase the rate of temperature rise.
Further, Patent Document 2 indicated below discloses a control device for a vehicle, which secures the emission clarification performance, without making a user feel uncomfortable, when CD (Charge Depleting mode) in which running with power of a motor only is preferentially performed is shifted to CS (Charge Sustain mode) in which running is performed with power of the engine and the motor, in a plug-in hybrid vehicle.